Perceived need to take medication is associated with medication non-adherence in patients with rheumatoid arthritis

Abstract

Background

This is the first cross-sectional study that aims to examine associations between beliefs about medication and non-adherence in patients with rheumatoid arthritis (RA) using disease-modifying antirheumatic drugs, taking potential psychological confounders into account.

Methods

Eligible patients (diagnosed with RA for ≥1 year or ≥18 years, using greater than or equal to one disease-modifying antirheumatic drug) were included by their rheumatologist during regular outpatient visits between September 2009 and September 2010. Included patients received questionnaires. The Beliefs about Medicines Questionnaire was used to measure the perceived need to take medication (necessity beliefs), the concerns about taking medication (concern beliefs), general medication beliefs, and attitudes toward taking medication. Medication non-adherence (no/yes) was measured using the Compliance Questionnaire Rheumatology (CQR). Associations between beliefs and non-adherence, and the influence of demographical, clinical, and psychological factors (symptoms of anxiety/depression, illness cognitions, self-efficacy) were assessed using logistic regression.

Results

A total of 580 of the 820 eligible patients willing to participate were included in the analyses (68% female, mean age 63 years, 30% non-adherent to their medication). Weaker necessity beliefs (OR [odds ratio]: 0.8, 95% CI [confidence interval]: 0.8–0.9) and an unfavorable balance between necessity and concern beliefs (OR: 0.9, 95% CI: 0.9–1.0) were associated with CQR non-adherence. Also, having an indifferent attitude toward medication (no/yes) was associated with CQR non-adherence (OR: 5.3, 95% CI: 1.1–25.8), but the prevalence of patients with an indifferent attitude toward medication was low. The associations were barely confounded by demographical, clinical, and psychological factors.

Conclusion

Increasing necessity beliefs about medication in clinical practice might be worthwhile in improving medication adherence in RA patients.

Keywords:

• medication non-adherence
• medication beliefs
• psychological confounders
• cross-sectional studies
• rheumatoid arthritis

Supplementary materials

To obtain a dichotomous Compliance Questionnaire Rheumatology (CQR) non-adherence score, first a discriminant Z score (which has been validated against a Medication Event Monitoring System [MEMS] taking compliance of ≤80%) has to be calculated.

The CQR has 19 items, which reflect statements about drug-taking behavior. Patients respond to a 4-point Likert scale ranging from 1, “don’t agree at all,” to 4, “agree very much”; items 4, 8, 9, 11, 12, and 19 have to be reversely recoded (4=1, 3=2, etc). Missing items are substituted with the patient’s average on all non-missing items when the amount of missing items is smaller than four; otherwise, no score is calculated. The Z score is calculated by means of the following function:

$\begin{array}{l}Z\text{score}=-3.4777-(0.4448*\mathrm{cqr}1)-(0.9517*\mathrm{cqr}2)\\ +(1.6758*\mathrm{cqr}3)-(0.2101*\mathrm{cqr}4)+\\ (0.0244*\mathrm{cqr}5)-(0.5353*\mathrm{cqr}6)+(0.003*\mathrm{cqr}7)+\\ (0.0135*\mathrm{cqr}8)-(0.0106*\mathrm{cqr}9)-(0.2546*\mathrm{cqr}10)\\ +(0.1023*\mathrm{cqr}11)+(0.1155*\mathrm{cqr}12)\\ +(0.0248*\mathrm{cqr}13)+(0.1091*\mathrm{cqr}14)\\ +(0.4475*\mathrm{cqr}15)+(0.2284*\mathrm{cqr}16)\\ +(0.535*\mathrm{cqr}17)-(0.4191*\mathrm{cqr}18)+\\ (0.6829*\mathrm{cqr}19).\end{array}$(1)

Non-adherence is defined when subjects have a Z score <−0.5849. For more information about the CQR, see de Klerk et al.¹

Table S1 Details of used questionnaires (except beliefs and adherence)

Table S2 The contribution of single, psychological factors to associations between beliefs about medication and CQR non-adherence (corrected for demographic and clinical factors)

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Acknowledgments

We would like to thank Peter Spreeuwenberg for his advice regarding the statistical analyses.

Disclosure

The authors report no conflicts of interest in this work.